Table 3: Prevalence of dementia (%) and its subtype by 10 years age group and by study site.

Age 70–79

Age 80–89

Age 90 and older

Study name/site

Prevalence in percentage (95% CI)

AD/VaD ratio

Prevalence in percentage (95% CI)

AD/VaD ratio

Prevalence in percentage (95% CI)

AD/VaD ratio

(Study years)

(Number of subjects screened)

Number of cases: all subtypes combined/AD/VaD

(Number of subjects screened)

Number of cases: all subtypes combined/AD/VaD

(Number of subjects screened)

Number of cases: all subtypes combined/AD/VaD

Hisayama (1985)

3.41 (1.92–5.56)

AD/VaD = 0.13

19.50 (13.65–26.52)

AD/VaD = 0.75

57.14 (28.86–82.34)

AD/VaD = 2.50

(440)

15/1/8

(159)

31/6/8

8/5/2

Hisayama 992

3.35 (2.00–5.25)

AD/VaD = 0.22

13.39 (9.34–18.37)

AD/VaD = 1.44

46.43 (27.51–66.13)

AD/VaD = 6.00

(537)

18/2/9

(239)

32/13/9

13/6/1

Okinawa (1991-1992)

3.67 (2.32–5.02)

AD/VaD = 0.59

14.93 (10.97–18.89)

AD/VaD = 2.10

36.83 (28.08–45.58)

AD/VaD = 3.66

(1481)*

45/16/27

(619)*

81/42/20

37/22/6

Hiroshima (1992–1996)

5.67 (4.09–7.66)

AD/VaD = 0.93

19.04 (14.97–23.87)

AD/VaD = 2.64

41.67 (26.97–61.50)

AD/VaD = 4.66

(741)

42/13/14

(

75/45/17

25/14/3

Hisayama (1998)

3.99 (2.65–5.76)

AD/VaD = 1.71

16.84 (12.76–21.59)

AD/VaD = 1.92

35.59 (23.55–49.13)

AD/VaD = 3.33

(676)

27/12/7

(

50/25/13

21/10/3

Tajiri (1998)

5.18 (3.80–6.93)

AD/VaD = N/A

22.33 (17.37–28.26)

AD/VaD = 1.50

51.52 (30.00–82.51)

AD/VaD = N/A

(908)

7/3/0#

22/12/8#

(

N/A

Hisayama (2005)

6.86 (5.13–8.94)

AD/VaD = 2.40

27.74 (20.50–29.37)

AD/VaD = 1.84

53.49 (42.41–64.32)

AD/VaD = 1.71

(729)

50/24/10

95/46/25

46/24/14

Ama-cho study (2008)

6.7 (4.12–9.02)

AD/VaD = 1.75

17.8 (14.81–26.41)

AD/VaD = 11.33

41.3 (26.51–61.52)

AD/VaD = 4.50

(432)

29/14/8

49/34/3

24/18/4

AD/VaD: the number of AD cases/the number of VaD cases.
#Based on subsample analysis with MRI results. N/A: sample size is too small to perform the calculation (AD + VaD cases < 5).
*Random sampling was used for screening. reported is not weighted. Prevalence, proportions of subtypes of dementia, and AD/VaD ratio used weighted frequencies to show those of the population at large.